The proximity is striking. Nusaybin, a Turkish town of about 80,000, sits on one side of the border. Qamishli, one of the biggest cities in northeast Syria, is on the other. A thin strip of land  fields, watchtowers and rows of barbed wire  is all that lies in between. "We're like one town separated by a fence," Nusaybin's Mayor Ayse Gokkan says, her third-story office overlooking the border area.

Nusaybin, like most cities in southeast Turkey, is predominantly Kurdish, as is Qamishli. Cross-border marriages are common, and most people on one side have at least a few relatives on the other. The towns' economies are intertwined  or used to be, until the Syrian government decided to close the border crossing three months ago.

Qamishli, though it has seen large protests since the beginning of the year-old revolution against the Syrian regime, has not suffered the kind of violence witnessed in Homs, Hama or Idlib. If and when it does, Gokkan promises, Nusaybin will be ready to help: the municipality has reached an agreement with local tribal chiefs to set aside 150 houses to receive fleeing Syrians. "We have experience with these kinds of things," says Gokkan. In the early 1990s, at the height of the war between the Turkish state and the separatist Kurdistan Workers' Party (PKK), Nusaybin residents opened their doors to Kurdish villagers fleeing scorched-earth attacks by the Turkish army. The conflict, which began with a PKK insurgency in 1984, has claimed 40,000 lives to date. Turkey, the U.S. and the European Union have labeled the PKK a terrorist organization.

Professions of Kurdish solidarity are not hard to come by on the Turkish side of the border. "History and politics divided the Kurds into four, but we are one people," says Gokkan. Turkey alone is home to 12 million to 15 million Kurds; Iran and Iraq to millions more. At least 2 million Kurds live in Syria, comprising 10% of the country's population. "We've learned that the Kurds cannot rely on anyone else," the mayor says.

But solidarity goes only so far. At the Turkish town's March 20 rally to celebrate Newroz, the traditional Kurdish New Year, speeches by Gokkan and other politicians from the pro-Kurdish Peace and Democracy Party (BDP) feature one or two shout-outs to the fellow Kurds over in the Syrian side, in Qamishli, but there are few direct references to their revolution. The main villain in Nusaybin is the Turkish state, not the Syrian one; the main enemy is Turkish Prime Minister Recep Tayyip Erdogan, not Syrian President Bashar Assad.

Perhaps most crucially, there's also the PKK. To most residents of Nusaybin, the organization is a champion of Kurdish rights, a symbol of resistance to decades of assimilationist politics and oppression at the hands of the Turkish state. However, to many of their cousins across the border, the group, whatever its record in Turkey, has become something else  one of the Assad regime's allies, if not an actual agent in the repression of antiregime sentiment among the Kurds of Syria.

As a recent study by the Henry Jackson Society, a British-based think tank, concludes, the PKK and Damascus, united by their hostility toward Turkey, have been engaged in "tactical cooperation." The PKK, according to the report, has helped the regime put down protests in Kurdish areas of Syria by "silencing other anti-regime opposition groups through violence."

"The PKK oppose any demonstration that opposes Bashar; they threaten to kill people," says Ibrahim, a young man who fled Qamishli this February. "Also, they have free movement. They set up checkpoints. They found Kurdish language and culture schools across Syria. You cannot do any of that without working with the government."

A confidential Baath-party strategy paper recently leaked to al-Jazeera TV by a Syrian defector appears to lend credibility to such claims. Outlining a number of steps to deal with the unrest in Aleppo, Syria's second largest city, the document allegedly recommends the following: "to place Kurdish areas under surveillance; and to coordinate with the Kurdistan Labour Party [PKK] in secret to quell protests and protesters."

It wouldn't be the first time that Damascus and PKK have entered a marriage of convenience. Throughout the 1990s, the Syrians hosted the leader of the PKK, Abdullah Ocalan, providing his fighters with access to training camps in the Lebanese Bekaa Valley and on the border with Turkey. It was only in late 1998, after Turkey threatened to invade Syria, that the regime sent Ocalan packing. (He was captured several months later and is now serving a life sentence in Turkey.) Over the subsequent decade, as Turkey's relations with Syria improved, Damascus began to crack down heavily against the PKK. According to Sertac Bucak, a former head of a minor Kurdish political party and a founding member of the Diyarbakir Institute for Political and Social Research, the rebellion against Assad's rule brought the process to a halt. Turkey's decision to side with the Syrian rebels convinced Assad to reverse the policy completely and once more embrace the PKK, says Bucak.